This invention relates to the use of molecules with adjacent carbonyl groups (Oxe2x95x90Cxe2x80x94Cxe2x95x90O), or related functional groups, that inactivate one or more prenyltransferases in cancer cells and thereby prevent the unrestrained division of cancer cells.
More than half of all human cancers contain a mutant gene that encodes a mutant protein known as Ras. In cancer cells, Ras activates the cells to divide in an unrestrained manner. To induce cell division, Ras must be localized at the inner surface of the cancer cell membrane. Membrane localization of Ras is effected by attachment of a hydrophobic group, typically the farnesyl group, which becomes attached to Ras. In some cells, the related geranylgeranyl group becomes attached instead. Both of these groups become attached to Ras enzymatically, in a process known as prenylation. Thus, interference with prenylation of Ras has the potential to prevent Ras localization at the inner surface of the cancer cell membrane, resulting in the cessation of unrestrained cell division of the cancer cell.
The enzyme that attaches the farnesyl group to Ras protein to facilitate the latter""s localization at the inner surface of the cancer cell membrane is farnesyl protein transferase, also known as protein farnesyltransferase (herein referred to as FTase). The famesyl group becomes attached to Ras by reaction with farnesyl diphosphate, a natural FTase substrate, also known as farmesyl pyrophosphate (herein referred to as FPP). In other words, FTase catalyzes the following reaction, in which Ras becomes attached to the farnesyl group by displacement of pyrophosphate (P2O74xe2x88x92, herein referred to as PPi): 
The newly formed farnesyl-Ras localizes at the inner surface of the cancer cell membrane and causes the cancer cell to divide without restraint.
There is a continuing need in the art for new ways to inhibit the growth of cancer cells. There is a need in the art for new ways to inactivate targets which are specifically involved in cancer progression and development.
It is an object of the invention to provide methods for inactivating prenylating enzymes.
It is another object of the invention to provide methods for screening test compounds for the ability to inactivate prenylating enzymes.
It is yet another object of the invention to provide methods for inhibiting the growth of a cancer cell.
It is still another object to provide pharmaceutical compositions for treating cancer.
It is another object to provide new compounds useful for treating cancers or inhibiting enzymes.
These and other objects of the invention are provided by one or more of the embodiments described below. In one embodiment a method of inactivating a prenylation enzyme is provided. The method comprises the step of contacting a prenylation enzyme with an xcex1-dicarbonyl compound having formula (I): R1-(Cxe2x95x90O)xe2x80x94(Cxe2x95x90O)xe2x80x94R2, wherein R1 is selected from the group consisting of hydrogen, alky, alkenyl, alkynyl, and aryl; and wherein R2 is selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, and aryl; and whereby the activity of the prenylation enzyme is reduced by at least 50%.
According to another embodiment of the invention, a method of screening compounds as anti-tumor agents is provided. The method comprises the step of contacting a test compound with a prenylation enzyme. The test compound has formula (I): R1-(Cxe2x95x90O)xe2x80x94(Cxe2x95x90O)xe2x80x94R2, wherein R1 is selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, and aryl; and R2 is selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, and aryl. Prenylation activity of the enzyme is measured. A test compound which reduces prenylation activity at least 50% is identified as a candidate anti-tumor agent.
According to another aspect of the invention a method of inactivating a prenylation enzyme is provided. The method comprises the step of contacting a prenylation enzyme with an xcex1-dicarbonyl compound having formula (II): R1-(Cxe2x95x90O)xe2x80x94(Cxe2x95x90O)xe2x80x94Lxe2x80x94(Cxe2x95x90O)xe2x80x94(Cxe2x95x90O)xe2x80x94R2, wherein R1, R2, and L are independently selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, and aryl. The activity of the prenylation enzyme is reduced by at least 50%.
According to another aspect of the invention a method of screening compounds as anti-tumor agents is provided. A test compound is contacted with a prenylation enzyme. The test compound has formula (II): R1-(Cxe2x95x90O)xe2x80x94(Cxe2x95x90O)xe2x80x94Lxe2x80x94(Cxe2x95x90O)xe2x80x94(Cxe2x95x90O)xe2x80x94R2, wherein R1, R2, and L are independently selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, and aryl. Prenylation activity of the enzyme is measured. A test compound which reduces prenylation activity at least 50% is a candidate anti-tumor agent.
Another embodiment of the invention provides yet another method of inactivating a prenylation enzyme. A prenylation enzyme is contacted with an xcex1-dicarbonyl compound having formula (III): Axe2x80x94Lxe2x80x94Dxe2x80x94R, wherein A is selected from the group consisting of an anionic group, a group that can spontaneously become anionic at physiological pH, and a group that can enzymatically become anionic at physiological pH; wherein L is a linker group; wherein D is a dicarbonyl functional group or a masked form of said group, and wherein R is selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, and aryl. The activity of the prenylation enzyme is reduced by at least 50%.
Still another aspect of the invention is a method of screening compounds as anti-tumor agents. A test compound is contacted with a prenylation enzyme. The test compound has formula (III): Axe2x80x94Lxe2x80x94Dxe2x80x94R, wherein A is selected from the group consisting of an anionic group, a group that can spontaneously become anionic at physiological pH, and a group that can enzymatically become anionic at physiological pH; wherein L is a linker group; R is selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, and aryl, and wherein D is a dicarbonyl functional group or a masked form of said group. Activity of the prenylation enzyme is measured. A test compound which reduces prenylation activity at least 50% is a candidate anti-tumor agent.
Also provided as an embodiment of the invention is a method of inhibiting growth of cancer cells. A cancer cell is contacted with an xcex1-dicarbonyl compound having a formula: R1-(Cxe2x95x90O)xe2x80x94(Cxe2x95x90O)xe2x80x94R2. R1 is selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, and aryl. R2 is selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, and aryl. The growth of the cancer cell is consequently inhibited.
Another aspect of the invention is a method of inhibiting the growth of a cancer cell in which a cancer cell is contacted with an xcex1-dicarbonyl compound having a formula: R1-(Cxe2x95x90O)xe2x80x94(Cxe2x95x90O)xe2x80x94Lxe2x80x94(Cxe2x95x90O)xe2x80x94(Cxe2x95x90O)xe2x80x94R2. R1, L, and R2 are independently selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, and aryl. The growth of the cancer cell is consequently inhibited.
Another embodiment of the invention is a method of inhibiting the growth of a cancer cell. A cancer cell is contacted with an xcex1-dicarbonyl compound having a formula: Axe2x80x94Lxe2x80x94Dxe2x80x94R. A is selected from the group consisting of an anionic group, a group that can spontaneously become anionic at physiological pH, and a group that can enzymatically become anionic at physiological pH. L is a linker group, and R is selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, and aryl. D is a dicarbonyl functional group or a masked form of said group. The growth of the cancer cell is consequently inhibited.
Also provided by the present invention is a pharmaceutically acceptable formulation. The formulation comprises a compound according to Formula I, Formula II, or Formula III, and a pharmaceutically acceptable excipient.
Additionally provided by the present invention is a compound according to Formula I, Formula II, or Formula III. The compound is not phenylglyoxal, biphenyldiglyoxaldehyde, 2-oxododecanal, or 2,3-pentanedione.
The present invention thus provides a method for hampering or preventing the proliferation of cancer cells, resulting in a decrease in tumor size and/or disappearance of the cancer. It acts by interference with cancer cell biochemistry, in which the enzyme famesyl protein transferase, geranylgeranyl protein transferase, and/or another prenylation enzyme acts on oncogenic proteins, such as RAS, or other growth-related cellular protein.